Europe is drawing up plans to build ground and flight demonstrators for commercial and regional aircraft, a compound helicopter and tiltrotor under a civil-aviation research program that will run from 2014-20.

The €3.6 billion ($4.7 billion) Clean Sky 2 program, funded 50:50 by government and industry, is being proposed as a follow-on to the €1.6 billion Clean Sky technology initiative now underway. But the final scale of the new effort will depend on the outcome of negotiations over funding for the European Union's Horizon 2020 research and innovation program, which has a projected budget of around €80 billion.

Clean Sky 2 will have two major aims. One is to take technologies developed under Clean Sky to a higher level of system maturity through more-integrated demonstrators, with the aim of meeting the environmental targets set by European industry in its Vision 2020. The other is to begin work on technologies needed to meet the more challenging longer-term objectives outlined by industry in its Flightpath 2050.

“We need to achieve the full Vision 2020 targets and start a new wave of technologies moving toward the Flightpath 2050 goals,” says Eric Dautriat, executive director of Clean Sky. “We need to go beyond the 2020 goals, to an intermediate step of 2030-35, and it needs to be started now.”

Launched in 2008, Clean Sky runs to 2017 and includes six integrated technology demonstrators for commercial and regional aircraft, business jets, rotorcraft and engines. Advances being developed under Clean Sky are projected to reduce aviation CO2 emissions by about 30%, against the Vision 2020 goal of 50% to 40% from technologies and 10% from air traffic management.

“There remains another 10% to reach the full Vision 2020,” says Dautriat. “In Clean Sky 2 we need to increase the maturity of technologies and increase the CO2 savings in parallel.” Where Clean Sky is “clearly focused on the environment,” Clean Sky 2's objectives will be “more than just environmental,” he says. The new research program will fit within the “smart and green transport” pillar of the EC's Horizon 2020, which has as targets the environment, mobility and competitiveness.

Whereas Clean Sky is aimed at increasing technology readiness levels (TRL) across a broad front, Clean Sky 2 will be focused on raising the readiness level of systems incorporating the new technologies. “We want to move to the maturity of the system rather than TRL only,” he says. “So we intend to deliver more highly integrated demonstrators than in Clean Sky.”

A Clean Sky 2 program outline submitted to the European Commission in July includes three higher-maturity integrated aircraft demonstrator programs (IADP), for large aircraft, regional airliners and rotorcraft. For rotorcraft, Clean Sky is developing separate technologies for airframes, engines, blades and systems, and Clean Sky 2 will integrate the technologies in flight demonstrators to determine if the expected performance can be achieved.

Plans call for two rotorcraft demonstrators: a compound helicopter that would follow on from Eurocopter's company-funded, 230-kt. X3 experimental aircraft; and a tiltrotor that would build on wind-tunnel testing of the 350-kt. Erica design led by AgustaWestland. The commercial- and regional-aircraft IADPs will each involve two or three ground or flight demonstrations that are more integrated than those conducted under Clean Sky.

Where Clean Sky will fly separate laminar-flow wing and open-rotor engine demonstrators (both based on Airbus A340s), “the wing and propulsion system will be flown together” in Clean Sky 2, says Dautriat. Advanced fuselage structures and more-electric systems developed under Clean Sky could also fly together in the follow-on program. The regional-aircraft IADP will focus on a turboprop airliner, he says.

A Safran-developed geared open-rotor engine will be one of the last demonstrators to fly under Clean Sky, and Dautriat expects development of the fuel-efficient propulsion system to continue under Clean Sky 2, but there is no plan to transfer work between the two programs. We are still on our way to testing the open rotor under Clean Sky” he says.

“There is an overlap of several years between Clean Sky 2 beginning in 2014 and Clean Sky ending in 2017, but the role of Clean Sky 2 is not to bring additional funding to Clean Sky projects but to build on Clean Sky,” Dautriat says. “The open-rotor demos will not answer every question, so we will probably continue the work on open rotors into Clean Sky 2.”

The second part of Clean Sky 2 will involve beginning work on raising the TRL of new technologies for the 2030-35 intermediate step toward meeting the goals set for Flightplan 2050, which include a 75% reduction in CO2. “These will not reach TRL 6 within Clean Sky 2, but we will get them to a lower TRL,” he says. TRL 6 is the level at which technologies are judged ready for use in full-scale development programs.

While debate has begun at the EC on future budget levels, industry is pushing ahead with building out the Clean Sky 2 proposal. Public consultations have been conducted and the process of involving potential participants is underway, starting with the industrial primes and demonstrator program leads, says Dautriat. The next step, next spring, will be a formal call for expressions of interest and initial research proposals. “We need participants to come forward with the first complete technical content,” he says.

“The final funding for Horizon 2020 is still unknown, so we do not know what our final budget will be,” says Dautriat. But, despite the budget pressures on European nations, €1.8 billion from industry for Clean Sky 2, matched by the equivalent public funding, is achievable within the EC's proposals for Horizon 2020, he believes.